1. Field of the Invention
The present invention relates to a recording medium suitable for recording with an ink, the recording medium having excellent ink absorbency, retaining the feeling of plain paper on the surface, and giving a high image density and a clear color tone. The present invention also relates to a process for producing the recording medium, and an image-forming method employing the recording medium.
2. Related Background Art
The ink-jet recording system records picture images and letters by ejecting fine ink droplets onto a recording medium like a paper sheet by a variety of principles for the ejection. The ink-jet recording system has features of high speed printing with low noise, ease of multicolor printing, flexibility in recorded pattern, needlessness of development and fixation of images, and so forth. Therefore, ink-jet recording systems have come to be employed widely as an image forming apparatus for information recording and other application fields.
Furthermore, the image formed by a multicolor ink-jet system can be comparable to the images formed by multicolor gravure printing or color photography, and is less costly in preparing a small number of print copies, so that the ink-jet recording systems are coming to be employed also in full color recording.
In ink-jet recording, the recording apparatuses and the recording methods have been improved for a higher recording speed, higher fineness, and full-color printing. With the improvement, the recording medium therefor is also required to have higher level properties.
Hitherto, various types of recording mediums have been disclosed to meet the above requirements. For example, Japanese Patent Application Laid-Open No. 55-5830 discloses an ink-jet recording paper sheet having an ink-absorbent coating layer provided on the surface of a supporting material. Japanese Patent Application Laid-Open No. 55-51583 discloses use of amorphous silica as a pigment in the coating layer. These recording mediums have, on a base material, an ink-receiving layer containing a pigment like alumina or silica. However, these recording medium cannot give a feeling of plain paper even though paper is used as the base material, owing to the ink-receiving layer formed on the base material.
Techniques are disclosed for obtaining a recording medium having the feeling of plain paper. Japanese Patent Application Laid-Open Nos. 6-312572, 7-25131, and 7-25132, for example, disclose recording mediums in which a paper base material is coated with a small amount of ultra-fine particles to keep the pulp fiber form on the recording face at a coverage of 70% or more by the ultra-fine particles. As another type of recording medium, for example, Japanese Patent Application Laid-Open No. 1-141783 discloses an ink-jet recording paper sheet coated with amorphous silica and alumina hydrate by machine coating, and Japanese Patent Application Laid-Open No. 11-174718 discloses a pigment-sized information-recording paper sheet.
On the other hand, recording paper sheets containing a filler or the like are also proposed. For example, Japanese Patent Application Laid-Open No. 53-49113 discloses a recording paper sheet which contains powdery urea-formalin resin internally and is coated and impregnated with a water-soluble polymer. Japanese Patent Application Laid-Open No. 58-8685 discloses a recording paper sheet which internally contains a synthetic silicate and glass fiber and is coated and impregnated with a water-soluble polymer. These techniques improves the ink absorbency of a non-sized paper sheet by incorporation of a fine powdery material.
As another type of the internally filled paper sheet, multilayered paper sheets are disclosed. For example, Japanese Patent Application Laid-Open No. 63-118287 and U.S. Pat. No. 4,734,336 disclose uncoated paper sheets of the laminated structure of a supporting layer composed of pulp fiber and a surface layer composed of a filler like silica and a fibrous material. Japanese Patent Application Laid-Open Nos. 1-78877, 2-243381, 2-243382, and 5-106197 disclose multilayered recording paper sheets, produced by combination-machining, with sizing on the base layer or on the interface between the base layer and the surface layer. Japanese Patent Application Laid-Open No. 6-219043 discloses a multilayered paper sheet carrying a slightly water-soluble or water-insoluble inorganic matter in the surface layer. Japanese Patent Application Laid-Open Nos. 6-287886, 7-5430, and 8-258400 disclose multilayered paper sheets employing a specified pulp such as bulky cellulose, mercerized cellulose, and bleached hardwood sulfite pulp. Japanese Patent Application Laid-Open No. 9-170190 discloses a multilayered paper sheet comprising a surface layer composed mainly of a hydrophilic fiber and a hydrophobic fiber and a base layer composed mainly of a cellulose fiber.
However, in high speed printing, conventional recording mediums cannot satisfy all the requirements for high ink absorbency, high color development density, less ink-feathering, and so forth.
An object of the present invention is to provide a recording medium suitable especially for ink-jet recording, the recording medium having excellent ink absorbency, retaining the feeling of plain paper on the surface, giving a high image density and a clear color tone. Other objects of the present invention are to provide a process for producing the recording medium, and to provide an image-forming method employing the recording medium.
The present invention has been made to solve the above problems, and intends to provide a recording medium which has high ink-absorbency, causes less dusting and less curling, having a feeling of plain paper on the surface, and is capable of giving high image density and giving a clear color tone, and is suitable especially for ink-jet recording; and also to provide a process for producing the recording medium, and an image-forming method employing the recording medium.
The above objects are accomplished by the present invention as described below. The recording medium of the present invention has a non-sized single-layer fibrous structure which is composed mainly of a fibrous material and contains no filler, and employs a face of the single-layer fibrous structure as an ink-receiving face, wherein alumina hydrate of a boehmite structure and a cationic resin are present at least near the surface of the fibrous material.
The process for producing the recording medium of the present invention comprises a step of applying alumina hydrate having a boehmite structure and a cationic resin onto a base material having a single-layer fibrous structure mainly composed of a fibrous material and containing no filler.
The image-forming method of the present invention is such an image-forming method for printing an image by applying ink droplets onto an ink-receiving face of the recording medium, wherein the recording medium having the aforementioned constitution is employed as the recording medium.
The present invention provides a recording medium which has high ink-absorbency, causing less dusting and less curling, retaining a feeling of plain paper on the surface, and being capable of giving high image density and giving a clear color tone. This recording medium is suitable for recording by application of ink, especially for ink-jet recording to obtain a recorded image with a high image recording density and a clear color tone by retaining the feeling of plain paper.